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| LTC3544_15 Datasheet, PDF (4/16 Pages) Linear Technology – Quad Synchronous Step-Down Regulator | |||
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LTC3544
ELECTRICAL CHARACTERISTICS
Note 3: TJ is calculated from the ambient temperature TA and power
dissipation PD according to the following formula:
TJ = TA + (PD)(68°C/W).
Note 4: This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed 125°C when overtemperature is active. Continuous
operation above the speciï¬ed maximum operating junction temperature
may impair device reliability.
Note 5: The LTC3544 is tested in a proprietary test mode that connects VFB
to the output of the error ampliï¬er.
Note 6: Load regulation is inferred by measuring the regulation loop gain.
Note 7: The QFN switch on-resistance is guaranteed by correlation to wafer
level measurements.
Note 8: Guaranteed by long-term current density limitations.
TYPICAL PERFORMANCE CHARACTERISTICS
VREF vs Temperature at 2.25V,
3.6V, 5.5V
0.815
0.810
CHANNEL 200A
ILOAD = 100mA
ALL CHANNELS OPERATING
0805
0.800
0.795
0.790
0.785
â50
VIN = 2.25V
VIN = 3.6V
VIN = 5.5V
0
50
100
TEMPERATURE (°C)
3544 G01
Switching Frequency vs Supply
Voltage and Temperature
3.0
ILOAD CHANNEL 100 = 50mA
ALL CHANNELS OPERATING
2.5
2.0
1.5
2
fOSC â40°C
fOSC 0°C
fOSC 25°C
fOSC 80°C
3
4
5
6
SUPPLY VOLTAGE (V)
3544 G02
Efï¬ciency vs Load Current 300mA
Channel. All Other Channels at
50% Peak Current
100
90
80
70
60
50
40 VIN = 3.6V
30
TA = 25°C
VOUT100 = 1.2V
20 VOUT200A = 0.8V
VOUT200B = 1.5V
10 VOUT300 = 1.8V
0 ALL OTHER CHANNELS LOADED 50%
0.0001 0.001
0.01
0.1
1
LOAD CURRENT 300mA CHANNEL (A)
3544B G03
Burst Mode Operation
300mA Channel
VOUT300
50mV/DIV
AC
COUPLED
SW300
5V/DIV
Burst Mode Operation
200mA, A-B Channels
VOUT200B
50mV/DIV
AC
COUPLED
SW2B
5V/DIV
Burst Mode Operation
100mA Channel
VOUT100
50mV/DIV
AC
COUPLED
SW100
5V/DIV
IL
100mA/DIV
VIN = 3.6V
VOUT = 1.8V
2μs/DIV
TA = 25°C
ILOAD = 20mA
IL
50mA/DIV
3544 G04
VIN = 3.6V
VOUT = 1.5V
2μs/DIV
TA = 25°C
ILOAD = 15mA
IL
50mA/DIV
3544 G05
VIN = 3.6V
VOUT = 1.2V
2μs/DIV
TA = 25°C
ILOAD = 12mA
3544 G06
3544fa
4
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